CH 14--Nervous System 6/PNS Degeneration

Question 1

3 TYPES OF Peripheral Nervous System Degeneration

1. _____________degeneration

Properties:

• Results from severe injury of neuron
• AXON starts to degenerate at peripheral end and extends back towards cell body (DYING back)
• Breakdown of myelin sheath and proliferation of Schwann cells.

Answer 1

AXONAL

Question 2

3 TYPES OF Peripheral Nervous System Degeneration

2. ___________ degeneration
   Properties:
   - Patchy dissolution of myelin sheath while axon preserved
   - Proliferation of Schwann cells = encircle, remyelinate denuded portion
   - Repeated episodes of demyelination & remyelination = concentric LAYERS of Shwann cell processes & collagen fibers (_________ __________)

Answer 2

Segmental

onion bulb

Question 3

3 TYPES OF Peripheral Nervous System Degeneration

3. _____________ degeneration

Properties:
A— Follows ___________ of nerve
B— DISTALLY axon & myelin sheath degenerate
C— Axon regenerates from PROXIMAL end down a tube of proliferating Schwann cells till motor end plate
D— Hematoma of SCAR may obstruct regenerating axon = PAINFUL mass (traumatic neuroma) and failure to retain function.

Answer 3

Wallerian

transection

Question 4

Peripheral Neuropathy

Properties:
A— Results from demyelination or axonal degeneration or both = failure of nerve _____________
B— Can involve several nerves (polyneuropathy) or only one nerve (mononeuropathy)

Answer 4

conduction

Question 5

1–Polyneuropathy:

• symmetrical
• either motor (muscle weakness), sensory (glove and stocking sensory loss) or both
• manifested in_________

2--Mononeuropathy:
- affection of \_\_\_\_\_\_\_\_\_\_ nerve (focal)
(e.g. carpal tunnel syndrome)
- asymmetric involvement of more than one 
nerve = mononeuropathy complex

Answer 5

extremities

single

Question 6

Peripheral Neuropathy

4 Types:

1. Metabolic neuropathy
2. Nutritional neuropathy
3. Inflammatory (Post-infection) neuropathy
4. Infectious neuropathy

Answer 6

KNOW THESE FOUR

Question 7

4 TYPES OF Peripheral Neuropathy

1. Metabolic neuropathy

3 Types of MN
1. __________ neuropathy
A—— Frequent complication in diabetes
B—— Distal, symmetric polyneuropathy
Causes:
i. thickening of wall of vasa vasorum ischemia
ii. accumulation of sorbitol, non-diffusible, osmotically active cellular swelling and death
2. Vitamin deficiency ——-(B1, B6, B12, E)
3. Amyloidosis——-Amyloidosis is a group of diseases in which one or more organ systems in the body accumulate deposits of abnormal proteins

Answer 7

Diabetic

Question 8

4 TYPES OF Peripheral Neuropathy

2. Nutritional Neuropathy

Etiology:

i. ___________ neuropathy
- diet limitation
- impaired B1 absorption
- chronic LIVER disease
ii. Deficiency of vitamins: B1, B6, B12, or E

Answer 8

Alcoholic

Question 9

4 TYPES OF Peripheral Neuropathy

3. Inflammatory (Post-infection) Neuropathy

A--Properties:
- one example is \_\_\_\_\_-\_\_\_\_\_\_\_\_\_ syndrome
B--Etiology: - unknown
- viral infection
- immune mediated
C--Clinically:- ascending flaccid paralysis, starting in lower limbs, may involve upper limbs & respiratory muscles
- mild or no sensory loss
- improves over several months

Answer 9

Guillain-Barré

*** Guillain-Barré syndrome is a serious health problem that occurs when the body’s defense (immune) system mistakenly attacks part of the nervous system.

Question 10

4 TYPES OF Peripheral Neuropathy

4. Infectious Neuropathy

Types:

1. ________: effect of exotoxin (sensory & motor)
2. ________: Schwann cells invaded by M. leprae
3. Varicella-zoster virus: latent infection of sensory ganglia, reactivation = vesicular lesions & pain along distribution of sensory nerves (thoracic, trigeminal)
4. AIDS

Answer 10

Diptheria

Leprosy